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Experimental investigation on effective aerosol scavenging using different spray configurations with pre-injection of water mist for Fukushima Daiichi decommissioning

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Nuclear Science and Techniques 2024年第5期35卷 154-172页

作者： Rui-Cong Xu Avadhesh Kumar Sharma Erdal Ozdemir Shuichiro Miwa Shunichi Suzuki Department of Nuclear Engineering and Management The University of Tokyo7‑3‑1 HongoBunkyo‑KuTokyo 113‑8656Japan Nuclear Professional School The University of Tokyo2‑2

During the decommissioning of the Fukushima Daiichi nuclear power plant,it is important to consider the retrieval of resolidified debris both in air and underwater *** the subsequent retrieval of debris from the reactor building,the resolidified debris must be cut into smaller pieces using various cutting *** the cutting process,aerosol particles are expected to be generated at the submicron *** has been noted that such aerosols sizing within the Greenfield gap(0.1-1μm)are difficult to remove effectively using traditional spraying ***,to improve the aerosol removal efficiency of the spray system,a new aerosol agglomeration method was recently proposed,which involves injecting water mist to enlarge the sizes of the aerosol particles before removing them using water *** this study,a series of experiments were performed to clarify the proper spray configurations for effective aerosol scavenging and to improve the performance of the water *** experimental results showed that the spray flow rate and droplet characteristics are important factors for the aerosol-scavenging efficiency and performance of the water *** results obtained from this study will be helpful for the optimization of the spray system design for effective aerosol scavenging during the decommissioning of the Fukushima Daiichi plant.

关键词： Fukushima Daiichi decommissioning Aerosol scavenging Multiphase flow Spray system Aerosol-mist agglomeration

Large-aperture Telescope Tracking Control Based on Time-synchronization Strategy

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Research in Astronomy and Astrophysics 2024年第3期24卷 34-46页

作者： Yun Li Yu Ye Shi-Hai Yang Ling-Zhe Xu Jin Xu Hai Wang Zhuang-Zhuang Deng Rui-Qiang Liu Xiao-Jie Gu Bo-Zhong Gu Nanjing Institute of Astronomical Optics&Technology Chinese Academy of SciencesNanjing 210042China CAS Key Laboratory of Astronomical Optics&Technology Nanjing Institute of Astronomical Optics&TechnologyNanjing 210042China University of chinese Academy of Sciences Beijing 100049China

A time-synchronization strategy for packetized transmission of target position about a large-aperture telescope observation control system has been proposed in this *** with the existing telescope tracking strategy,the target position packing and sending strategy based on the time synchronization method proposed in this paper has the advantages of high stability and ***,the telescope tracking observation control method was elaborated in this paper,including the motion pattern during telescope ***,the strategy for packetizes transmission of target positions based on time-synchronization is established and lists the detailed ***,the performance of the tracking strategy is verified using the 2.5 m telescope for the simulated uniform speed star and the blind-tracking fixed star HIP 31216,*** test results show that the accuracy root mean square of the tracking strategy proposed in this paper is less than 0".02 at 30 minutes,and the performance is much better than the design requirement of 0".*** most important advantage of this tracking strategy is that the telescope can guarantee normal tracking for a certain period of time even if the hardware or software of the host computer is abnormal.

关键词： miscellaneous-telescopes-methods observational-methods analytical

The shear strength of the interface between artificial rock and printed concrete at super-early ages

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Frontiers of Structural and Civil Engineering 2024年第1期18卷 51-65页

作者： Yong Yuan Xiaoyun Wang Jiao-Long Zhang Yaxin Tao Kim Van Tittelboom Luc Taerwe Geert De Schutter College of Civil Engineering Tongji UniversityShanghai 200092China State Key Laboratory of Disaster Reduction in Civil Engineering Tongji UniversityShanghai 200092China Belgium-China Joint Laboratory for Industrialized Construction Tongji UniversityShanghai 200092China Magnel-Vandepitte Laboratory for Structural Engineering and Building Materials Ghent UniversityGhent 9052Belgium

3D concrete printing has the potential to replace shotcrete for construction of linings of tunnels in hard *** shear strength of the interface between rock and printed concrete is vital,especially at super-early ***,traditional methods for testing the shear strength of the interface,e.g.,the direct shear test,are time-consuming and result in a high variability for fast-hardening printed *** this paper,a new fast bond shear test is *** test can be completed in 1 min,with another 2 min for preparing the next *** influence of the matrix composition,the age of the printed matrices,and the interface roughness of the artificial rock substrate on the shear strength of the interface was experimentally *** tests were conducted at the age of the matrices at the 1st,the 4th,the 8th,the 16th,the 32nd,and the 64th min after its final setting.A dimensionless formula was established to calculate the shear strength,accounting for the age of the printed matrices,the interface roughness,and the shear failure *** was validated by comparing the calculated results and the experimental results of one group of samples.

关键词： rock tunnel printed concrete interface fast bond shear test shear strength

A method of determining typical meteorological year for evaluating overheating performance of passive buildings

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Building Simulation 2023年第4期16卷 511-526页

作者： Bin Qian Tao Yu Chen Zhang Per Heiselberg Bo Lei Li Yang School of Mechanical Engineering Southwest Jiaotong University610031 ChengduChina Department of Built Environment Aalborg UniversityAalborg9100Denmark

In the simulation of building overheating risks,the use of typical meteorological years(TMY)can greatly reduce the simulation workload and accurately reflect the distribution of simulation results according to the weather conditions over a given ***,all meteorological parameters in most current TMY methods use a uniform weighting factor which may make the simulation results against the actual simulation results of the period and negatively affect the accuracy of the evaluation *** addition to differences in climate characteristics between climate zones,the sensitivity of different simulation results to external parameters will also be ***,a TMY method based on the Finkelstein-Schafer statistical method is proposed,which considers the climatic characteristics of different regions and the correlation with the output parameters of indoor simulation to select the typical *** proposed method is demonstrated in the three future scenarios for the three cities in different climate zones in *** results show that the traditional TMY method has an overestimated weight of solar radiation and wind speed and an undervalued weight of dry bulb temperature when indoor temperature-related indicators are the output *** with the traditional TMY method,the TMY generated by the improved method is closer to the distribution characteristics of the long-term outdoor weather ***,when using the improved TMY data to evaluate the overheating performance of the passive residential buildings,the difference of the results of the unmet degree hours,indoor overheating degree,and the overheating escalation factor between the long-term projected data and the TMY data can be reduced by 63%–67%compared with the traditional TMY data.

关键词： passive buildings overheating typical meteorological year Finkelstein-Schafer statistical method

Numerical study on the strain capacity of girth-welded X80 grade pipes

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Petroleum Science 2022年第5期19卷 2399-2412页

作者： Xu Wang Jian Shuai Sheng-Zhu Zhang Wei Ren Xue-Ming Zhu College of Safety and Ocean Engineering China University of PetroleumBeijing102249China Department of Structural Engineering Norwegian University of Science and Technology(NTNU)Trondheim7491Norway China Academy of Safety Science and Technology Beijing100012China

Strain capacity is an important performance indicator for designing and evaluating high-grade steel *** to the inhomogeneity of material properties in welded structures,girth welds are one of the main factors that restrict the strain capacity of *** this paper,girth-welded pipes with cracks in the inner surface of the weld have been studied,and the ductile crack initiation and propagation behavior have been simulated using the Gurson *** corresponding nominal strain at the onset of crack initiation was defined as the characteristic value of strain *** influencing factors on the strain concentration area,strain concentration factor,and strain capacity of girth-welded pipes were quantitatively analyzed.A semiempirical calculation formula for the strain capacity of typical girthwelded X80 grade pipes has been proposed as a function of the crack size,mismatch coefficient of the weld,and softening degree of the heat affected zone(HAZ).This study can facilitate the defect assessment of girth-welded pipes.

关键词： Strain capacity Girth-welded X80 grade pipes Mismatch and softening

Influence of temperature on twinning dominated pop-ins during nanoindentation of a magnesium single crystal

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Journal of Magnesium and Alloys 2022年第1期10卷 183-194页

作者： Jun Cheng Tingting Guo Matthew R.Barnett School of Materials and Energy Guangdong University of TechnologyGuangzhouGuangdong 510006China Institute for Frontier Materials Deakin UniversityGeelongVictoria 3216Australia School of Materials Science and Chemical Engineering Xi'an Technological UniversityXi'an cityShaanxi 710021.China

The present paper examines the temperature sensitivity of tensile twinning in a magnesium single crystal during nanoindentation of the prismatic plane. High temperature indentations from 25 ℃ to 250 ℃ were employed on a well polished magnesium single crystal {10-10}plane. For a indentation curve displaying a pop-in, a single twin was seen on the sample surface using Atomic Force Microscopy(AFM)imaging. For indentations that produced no pop-in, no twinning was observed. We thus conclude the pop-in arises from a twinning event in the present case. With increasing temperature, the mean pop-in load(measured from 200 repeat indentations of each testing temperature)drops markedly. This is interpreted by the thermal activation of nucleation of lattice dislocations, which immediately trigger a twinning *** activation analysis yields activation energies that are consistent with this idea. With increasing temperature the pop-ins became deeper and the twins, after further indentation, showed more growth. It is likely that non-basal slip is activated in the stress concentrations that arise during twinning and the thermal activation of this slip accounts for the observed temperature effects. It is concluded that in interpreting the temperature sensitivity of twinning stresses, any associated lattice dislocation activity must be considered.

关键词： Magnesium single crystal Twinning Temperature Nanoindentation

Fabrication of monodispersed B,N co-doped hierarchical porous carbon nanocages through confined etching to boost electrocatalytic oxygen reduction

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Nano Research 2023年第1期16卷 290-298页

作者： Xuefei Wang Chao Han Haitao Li Panpan Su Na Ta Yanfu Ma Zhenguo Huang Jian Liu School of Civil&Environmental Engineering University of Technology SydneySydneyNSW2007Australia State Key Laboratory of Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China DICP-Surrey Joint Centre for Future Materials University of Surrey GuildfordSurreyGU27XHUK

Dual heteroatom-doped carbons have attracted widespread research attention as catalysts in the field of energy storage and conversion due to their unique electronic structures and chemical *** particular,boron and nitrogen co-doped carbon(B,N@C)has shown great potential for photo/electrocatalytic ***,more needs to be done for rational designing and regulating the structure of these materials to improve their catalytic ***,monodispersed hierarchical porous B,N@C nanocages were fabricated by pyrolyzing zeolite imidazole framework(ZIF)which was treated with ammonia borane or boric acid via an integrated double-solvent impregnation and nanocofined-etching *** treated ZIF-8 provided an essential structural template to achieve B,N co-doped hierarchical structures with micro/meso/macro multimodal pore size *** resultant B,N@C nanocages displayed high catalytic activities for electrochemical oxygen reduction reaction(ORR)in alkaline media,outperforming most carbon-based catalysts,particularly from the perspective of the half-wave *** high catalytic performance is due to the enhanced activity by the coexistence of B and N and the mass transfer promoted by the unique hierarchical porous structure.

关键词： heteroatom doping hierarchical porous carbon host-guest chemistry confined etching electrocatalysis mass transfer

单电子还是双电子?反应底物决定的铁催化未活化烷基卤代物与胺、酰胺和吲哚的酰胺化反应机理

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chinese Journal of Catalysis 2023年第4期47卷 121-128页

作者：艾汉均赵丰乾吴小锋莱布尼茨催化研究所德国罗斯托克中国科学院大连化学物理研究所辽宁大连116023

铁廉价,储量丰富,铁基催化剂具有独特的催化活性,其催化的羰基化反应备受化学家关注.烷基溴类化合物具有较高的解离能,酰胺和吲哚类化合物具有弱亲核性,上述性质使其发生羰基化转化具有一定的挑战性.本文发展了一种铁催化的酰胺化反应,... 详细信息

铁廉价,储量丰富,铁基催化剂具有独特的催化活性,其催化的羰基化反应备受化学家关注.烷基溴类化合物具有较高的解离能,酰胺和吲哚类化合物具有弱亲核性,上述性质使其发生羰基化转化具有一定的挑战性.本文发展了一种铁催化的酰胺化反应,使用羰基铁催化剂前体,在反应体系中原位生成低价态的活性铁催化中心,并对烷基类底物进行活化.随后发生一氧化碳对碳铁键的插入、酰基铁的生成、亲核试剂的进攻等反应,最后生成目标产品.在该催化体系作用下,未活化的烷基卤代物可以与胺、酰胺和吲哚发生反应,得到较高收率的酰胺、酰亚胺和N-酰基吲哚等化合物,并表现出较好的官能团兼容性.实验发现,含有天然产物骨架的原料也能够高效转化.在反应机理方面,本文进行了分子内、分子间自由基捕捉等研究,结合已报道的谱学研究结果,推断出低价态铁催化中心的存在.结合实验数据以及反应机理研究结果认为,该反应的反应历程是由底物决定的:当以烷基碘类化合物为原料时,经历的是单电子转移(自由基)过程;当以烷基溴类化合物时,经历的是双电子转移过程.综上,本文发展了一种铁催化的烷基卤代物的酰胺化反应,为烷基酰胺合成提供一定参考.

关键词：铁催化羰基化偶联烷基卤代物酰胺酰亚胺

Effect of FeO on the formation of spinel phases and chromium distribution in the CaO-SiO_2-MgO-Al_2O_3-Cr_2O_3 system

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International Journal of Minerals,Metallurgy and Materials 2013年第3期20卷 253-258页

作者： Jian-li Li An-jun Xu Dong-feng He Qi-xing Yang Nai-yuan Tian State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Division of Sustainable Process Engineering Lule University of Technology

Synthetic slag samples of the CaO-SiO2-MgO-A1203-Cr203 system were obtained to clarify the effect of FeO on the formation of spinel phases and Cr distribution. X-ray diffraction （XRD） and scanning electron microscopy （SEM） equipped with energy-dispersive spectroscopy （EDS）, as well as the thermodynamic software FactSage 6.2, were used for sample characterization. The results show that the addition of FeO can decrease the viscosity of molten slag and the precipitation temperatures of melilite and merwinite. The solidus temperature significantly decreases from 1400 to 1250℃ with the increase of FeO content from 0wt% to 6wt%. The addition of FeO could enhance the content of Cr in spinel phases and reduce the content of Cr in soluble minerals, such as merwinite, melilite, and dicalcium silicate. Hence, the addition of FeO is conducive to decreasing Cr leaching.

关键词： stainless steel slags spinel phase chromium leaching ferrous oxide